表 act
id conetent type time
1 aaa 1
2 cc 1
3 aacc 2
4 bbcc 2
5 3333 3

[PHP]
SELECT
COUNT(a.id) AS PHP,COUNT(b.id) AS ASP,COUNT(c.id) AS JSP
FROM act a
JOIN act b ON(b.type='1')
JOIN act c ON(c.type='2')
WHERE a.type='3'
[/PHP]

这样写不能得到正确的结果 那里错误了?